In a current LTE (Long Term Evolution) protocol, RRM (Radio Resource Management) measurement quantities include: RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality). RSRP reflects strength of a received signal, and RSRQ reflects channel quality, where RSRQ is related to load of a local cell and a neighboring cell. Currently defined RSRP measurement and RSRQ measurement are both based on a CRS (Cell-specific Reference Signal) transmitted by a cell. In a time domain, a CRS in an existing cell is transmitted in every subframe; therefore, for the RSRP measurement and RSRQ measurement, it is unnecessary to specify subframes in which UE (User Equipment) performs measurement. In a frequency domain, CRSs are scattered in entire system bandwidth; therefore, the UE may perform measurement in six central PRBs (Physical Resource Block) or in measurement bandwidth delivered by a system.
Related content of measurement in 3GPP (3rd Generation Partnership Project) protocol release 8/9 (Rel-8/9) is generally as follows:
Measurement quantity: measurement quantities in Rel-8/9 are RSRP and RSRQ. The UE reports RSRP/RSRQ periodically or after an event is satisfied.
Measurement period: a current specification for RSRP and RSRQ measurement bandwidth is embodied in a MeasObjectEUTRA field in system messages SIB3 (System Information Block 3) and SIBS and RRC (Radio Resource Control) signaling, and is embodied by using an AllowedMeasBandwidth IE (Information Element), where AllowedMeasBandwidth represents maximum allowed measurement bandwidth. In other words, the UE may perform measurement of bandwidth less than AllowedMeasBandwidth. Because the UE reports only RSRP/RSRQ, a network side cannot know how much measurement bandwidth is used by the UE.
In the frequency domain, measurement performed by the UE is based on measurement bandwidth. The measurement bandwidth may be the six central PRBs. Alternatively, referring to AllowedMeasBandwidth transmitted by a network, the UE performs measurement according to measurement bandwidth greater than the six PRBs. The UE only needs to satisfy a requirement of measurement precision.
In the time domain, the UE may currently perform measurement based on any subframe, which is not limited at all in standards. Typically, in a specific measurement period, the UE may collect multiple subframes at equal intervals to perform RSRP or RSRQ measurement to obtain measurement results, and then perform averaging on the multiple measurement results corresponding to the multiple subframes, so as to reduce impact of radio channel fading on RSRP or RSRQ measurement precision.
NCT (New Carrier Type) is introduced in a discussion about R12 standards. In these carrier types, CRS transmission is different from a current CRS transmission mechanism in the frequency domain and the time domain, so that a current UE measurement mechanism cannot work normally in an NCT scenario. Therefore, how to perform measurement in a new carrier type needs to be redefined.